[FEATURE REQUEST] ElGamal Encryption Algorithm

[Shewale41]

What would you like to Propose?

Title: Add ElGamal Encryption and Decryption Algorithm Implementation

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🧠 Overview

I propose implementing the ElGamal encryption scheme, a public-key cryptosystem based on discrete logarithms. It will be a great addition to the ciphers module alongside RSA and other cryptographic algorithms.

🧩 Problem Description

Implement ElGamal key generation, encryption, and decryption in Java using modular arithmetic. Demonstrate how random keys ensure semantic security.

📂 Implementation Details

• Folder: src/main/java/com/thealgorithms/ciphers/
• Filename: ElGamalCipher.java
• Approach:
  • Generate keys (p, g, x, y) where y = g^x mod p.
  • Encrypt message m using random k.
  • Decrypt ciphertext (c1, c2) using m = c2 * (c1^x)^-1 mod p.

✅ Expected Deliverables

• Fully functional implementation with key generation, encryption, and decryption.
• Example in main() demonstrating encryption/decryption of small integers or strings.
• Comments explaining modular arithmetic and randomization.
• Basic test cases and verification of decryption correctness.

🧑‍💻 Additional Notes

ElGamal is mathematically rich and deepens understanding of asymmetric encryption in the Algorithms repo.

Issue details

🧩 Problem Description

Implement ElGamal key generation, encryption, and decryption in Java using modular arithmetic. Demonstrate how random keys ensure semantic security.

Additional Information

No response